Do power cords make an audible difference?

I recently discovered the inexpensive Pangea AC-9 power cord. It was so inexpensive I decided, just for kicks, to buy one for my sacd player and my integrated amp. I was extremely doubtful I would hear any difference at all. I plugged them in, turned on the system and I was surprised. I immediately invited a non-audiophile over for a listen. She had only heard my system for maybe 30 minutes with the old cords and I asked her if she could hear a difference. After listening to only two tracks she said "it sounds more clear". This is exactly what I had thought. I also noticed the sound stage seemed bigger. Now, it's not A huge difference but it is noticeable to the casual observer, so it is significant, which is more than I hoped for.